Adjusting means for a lamp structure



June 26, 1962. J. JACOBSEN ADJUSTING MEANS FOR A LAMP STRUCTURE 2 Sheets-Sheet 1 Filed April 12, 1960 June 26, 1962 J. JACOBSEN 3,

ADJUSTING MEANS FOR A LAMP STRUCTURE Filed April 12, 1960 2 Sheets-Sheet 2 1 .FIGA FIG.3

: lhi z li INVENTOR ATTORNEY United States Patent 3,041,060 ADJUSTING MEANS FOR A LAMP STRUCTURE Jacob Jacobsen, Ekelyveien 10, Oslo, Norway Filed Apr. 12, 1960, Ser. No. 21,800 Claims. (Cl. 267-1) The present invention relates to adjusting means for a lamp structure comprising at least one by means of tension springs equipoised parallelogram linkage assembly.

The object of such lamp structures is that the lamp should be set in any desired position and thereby remain in this position. This effect is not easy to obtain as the weight of the lamp may change by changing the light source, by changing the lamp reflector and the spring tension may vary with time. To obtain an approximate correction of such eventualities it is known by such lamp structures to arrange in the bar-s more than one anchorage hole for at least one end of the spring, so as to enable a step by step tensioning of the spring. Such a step by step tensioning has proved not to be satisfying.

The main object of the present invention is therefore by such a lamp structure to provide a continuous adjustment of the spring tension.

This is according to the invention achieved in that at least one end of each spring is connected to a fixed on the structure rotatable member, by means of a screw which is freely rotatable in said member, in such a way that the spring tensioning may be continuously adjusted by rotation of the screw either by hand or by means of a screw driver.

In a preferred embodiment according to the invention, the threaded part of each screw engages a nut fixed to the spring end.

In another embodiment according to the invention the diameter of the end of the spring coil is contracted to engage the threaded part of the screw.

To stiffen the spring ends is, according to the invention, each end of the spring surrounded 'by a cover which by means of a transverse opening is supported on the said member and fixed by the screw which extends through an opening in the end of the cover.

To prevent dust concentration in the spring and to give the structure a better look, are according to the invention the covers extended and given different diameters so as to overlap each other telescopically.

Some embodiments of the invention will be more detailed explained with reference to the accompanying drawing.

FIG. 1 shows an over-all perspective view of a lamp structure with adjusting means according to the invention.

FIG. 2 shows one embodiment of the invention.

FIG. 3 shows a second embodiment according to the invention. a

FIG. 4 shows a third embodiment according to the invention.

In FIGURE 1 a lamp structure 1 is clamped to a table or desk 2 by means of a base member 3. The structure 1 has an upper pivoted lever assembly 5 comprising the bars and 11 and a lower pivoted lever assembly 4, comprising the bars 6 and 7, the lower end of which is pivoted to a swivel bearing member 8 which cooperate with the base member 3. The upper end of the lower lever 4 and the lower end of the upper lever 5 are connected pivotally by means of a member 9. The upper end of the upper lever 5 being by means of a member 12 pivotally connected to the lamp reflector 13.

In FIGURE 2 support members 22 are pivotally fastened on two diiferent parts of the lamp structure 21. The spring 23 which serves as equipoising means, at both ends is provided with a nut 24 for screws 25 which extend through holes 28 in the members 22. By

ice

turning the screw 25 the spring 23 is tensioned to a desired degree. Surrounding the ends of the spring are covers 26, for instance of metal or plastic, which by means of a transverse opening 27 is supported on the member 22, an opening 29 in the end of the cover 26 forming base for the head of the screw 25. The lower cover in FIGURE 2 has a throughgoing opening 27 for instance for the arrangement of more than one spring on the same support member 22.

In FIGURE 3 support members 32 are pivotally fastened on two different parts of the lamp structure 31. The spring 33 has in both ends 34 contracted diameter so that the spring ends engage the threaded part of the screws 35. In this case the ends of the spring are also provided with a cover 36 which by means of a transverse opening 37 is supported on the member 32 and fixed by the screw 35 which extends through an opening 39 in the end of the cover 36. The spring 33 is tensioned by turning the screw 35 by means of a screw driver.

In FIGURE 4 support members 42 are pivotally fastened on two different parts of the lamp structure 41. The spring 43 is at both ends provided with a nut 44 for screws 45 which extend through holes 48 in the members 42. In this case the covers 46 are extended and given different diameters so as to overlap each other telescopically and thereby surrounding the whole spring 43. By means of transverse openings 47 in the end of the covers, these are supported on the members 42, an opening 49 in the end of the cover 46 forming base for the head of the screw 45. The head 50 of the screws 45 is adapted to be operated by hand for adjustment of the spring tension.

I claim:

1. In an equipoised lamp mechanism which includes a linkage assembly comprising first and second parallelogram linkages and an intermediate frame member pivotally interconnecting the linkages in end-to-end relationship and a base frame member pivotally connected to the other end of one of said linkages and a top frame member pivotally connected to the other end of the other of said linkages and a lamp construction mounted upon said top frame member; a pair of spring assemblies one of which is connected at one end to said base frame member and at the other end to the adjacent parallelogram linkage, the other of said spring assemblies being connected at one end to said intermediate frame and at the other end to the other of said parallelogram linkages, one of said spring assemblies including an extensible tight-wound tension spring, means at each end of said spring providing for threaded engagement with a screw, a pair of screws threaded respectively into the last-named means, means fixed respectively to the frame member and the parallelogram linkage and providing an opening in which the adjacent screw is held and permitted to turn thereby to provide for adjusting the tension of the spring by turning the screw, and a pair of covers fixed respectively to the last-named means and covering the adjacent end of the spring and the connecting portion of the screw.

2. Apparatus as described in claim 1, wherein the means at each end of said spring providing threaded engagement with the screw comprises a cylindrical plug threaded into the end of the screw and having a threaded bore into which the screw is threaded.

3. Apparatus as described in claim 1 wherein the means at each end of said spring providing threaded engagement with the screw comprises the end portion of the spring which is reduced in radius so as to form a screw thread.

4. Apparatus as described in claim 1 which includes a pair of telescoped sleeves enclosing said spring and connected respectively to move with the screws.

5. In an equipoised lamp mechanism which includes a linkage assembly comprising first and second parallelogram linkages and an intermediate frame member pivotally interconnecting the linkages in end-to-end relationship and a base frame member pivotally connected to the other end of one of said linkages and a top frame member pivotally connected tothe other end of the other of said linkages and a lamp construction mounted upon said top frame member; a pair of spring assemblies one of which is connected at one end to said base frame member and at the other end to the adjacent parallelogram linkage, the other of said spring assemblies being connected at one end to said intermediate frame and at the other end to the other of said parallelogram linkages, one of said spring assemblies including an extensible tight-wound tension spring, support means for said spring fixed respectively to the frame member and to the parallelogram linkage and including a bracket having an opening, a screw held in said opening, a cylindrical plug nested within one end of said spring and having a threaded axial bore engaging said screw thereby to provide for adjusting the tension of the spring by turning the screw, and a pair of covers, one of which is fixed to the support means and covering and connected to the adjacent end of the spring, and the other cover being fixed to the support means and covering the other end of said spring and the connecting portion of said screw.

References Cited in the file of this patent UNITED STATES PATENTS 836,811 Kennebrew Nov. 27, 1906 1,966,957 Dunn July 17, 1934 2,090,439 Carwardine Aug. 17, 1937 2,129,338 Timmons Sept. 6, 1938 2,265,629 Christiansen Dec. 9, 1941 2,787,434 J acobsen Apr. 2, 1957 FOREIGN PATENTS 179,826 Austria Oct. 11, 1954 

